This invention relates to ultrasonic testing devices, and more particularly, to a method and apparatus for detecting flaws, cracks and the like along the base of a track rail.
Ultrasonic testing of track rails utilizes ultrasonic vibrations, as generated by an electro-acoustic transducer in the form of a piezo-electric quartz crystal, which is electrically energized at high frequency for conversion of the electrical oscillations into mechanical oscillations. The crystal engages the rail through a fluid couplant and is moved along the extent of the track rail. Heretofore, resulting ultrasonic search beams have been directed through the web and running surface of the rail under test with at least the associated reflected beams being monitored to determine whether the transmitted beams encountered any flaws in the tested areas. Generally speaking, a reflected signal of the same strength as the transmitted signal indicates a flawless rail with a weakening of the reflected or return signal associated with the transmitted signal indicating internal flaws within the rail. There are various means for monitoring the transmitted and reflected beams/signals, one such means being shown by my U.S. Pat. No. 3,156,111 which is hereby incorporated by reference herein. In this patent, transmitted and echo signals are represented on a cathode ray tube that are readily understandable pictorial representations of certain internal structural characteristics of a track rail.
In the past, flaw testing has been concentrated on the top running surface of the rail and the web extending therebetween. However, the manufacturers of such rails are now using roller-type straightners to straighten the rails so as to expedite production. These straightening devices may produce flaws, cracks etc., in the bottom of the base of the rail usually first recognizable only after the track rail has been put into service. Thus, it is now desirable to have a method for predetection of such flaws in the base of the rail utilizing ultrasonic testing techniques and performing apparatus to easily effect such testing.
Accordingly, I have invented methods and accompanying apparatus designed to detect flaws, cracks etc., in the base of the rail particularly along the bottom surface thereof. Generally, my apparatus comprises a sliding shoe relatively movable along the top surface of the base of the rail which is adjacent the web thereof. Mounted on the sliding shoe in movement therewith is a transducer element along with fluid means for providing a wedge of water between the transducer and the top surface of the rail which acts as the ultrasonic coupling medium therebetween. The coupling medium cooperates with the user-selectable orientation of the transducer unit relative to the top surface of the rail base so as to transmit ultrasonic waves throughout the rail base particularly along the bottom surface thereof. Base echoes and return echoes, corresponding to the transmitted and reflected signals, are displayed on a cathode ray tube in a manner as set forth in my above-identified patent so that a visual inspection can be made of these signals to determine the absence or presence of defects in the rail base. The relative movement of the apparatus along the extent of the rail provides for a succession of such transmitted and reflected signals and thus a continuous testing therealong.
Accordingly, it is a general object of this invention to provide a method and performing apparatus for detecting defects in the base of a track rail.
Another object of this invention, as aforesaid, is to provide apparatus for housing an electromechanical transducer and coupling medium in relative movement along the base of the rail so as to transmit and receive ultrasonic signals relative therealong.
Still another object of this invention, as aforesaid, is to provide apparatus which continuously interposes said coupling medium between the transducer and the surface of the rail base.
A more particular object of this invention is to provide apparatus, as aforesaid, at which the angle of the entry of the ultrasonic signal, as emitted by the transducer relative to the rail base, is operator-adjustable to assure that the ultrasonic waves scrub the bottom surface of the rail base.
Other objects and advantages of this invention will become apparent from the following description taken in connection with the accompanying drawings, wherein is set forth by way of illustration and example, embodiment of this invention.